Refrigerant control means for maintaining multiple temperatures



1959 o. D. MARTIN 2,914,925

REFRIGERANT CONTROL MEANS FOR MAINTAINING MULTIPLE TEMPERATURES I Filed April 24. 1956 ""i iiiiiiiiiiiiiiiiiiiiD nllr Gaiiiauuumnmmm l 0m 12 MW, 1 nusu znlemi By I 36 /J0 W d. M

United States Patent Ofiice 2,914,925 Patented Dec. 1, 1959 REFRIGERANT CONTROL MEANS FOR MAIN- TAINING MULTIPLE TEMPERATURES Owen D. Martin, Farmington Township, Oakland County,

Mich., assiguor to American Motors Corporation, Detroit, Mich., a corporation of Maryland Application April 24, 1956, Serial No. 580,348

1 Claim. (Cl. 62-197) This invention relates to refrigerating apparatus and more particularly to such apparatus in which multiple temperatures are maintained.

It is an object of the present invention to provide in a refrigerating system having an evaporator for cooling and maintaining a compartment at relatively high temperatures for storage of articles of food and a second evaporator for cooling and maintaining a second compartment at relatively low temperatures for freezing and storing frozen foods and the like whereby the evaporators are interconnected in series refrigerant flow circuit by a plurality of fixedrestrictor conduits to regulate the flow therethrough to maintain the compartments at the desired temperatures and a control valve controlling the flow through one or more of the restrictor conduits to increase or decrease the flow of refrigerant from the first evaporator to the second in accordance to refrigerant needs.

Another object of the present invention is to provide in a two temperature refrigerating system having an evaporator operable for cooling and maintaining a compart ment at temperatures above 32 F. and a second evaporator for cooling and maintaining a second compartment at temperatures below 32 F. wherein refrigerant is conducted to the evaporators through a plurality of fixed restrictor conduits arranged wherein one or more of the restrictor conduits are controlled by a valve operably responsive to ambient temperatures to select a restrictor conduit that will increase or decrease the flow of refrigerant to one of the evaporators in accordance to refrigerant needs relative to ambient temperatures.

A further object of the present invention is to provide in a two temperature refrigerating system whereby the refrigerant is conductedthrough fixed restrictor conduits' of different flow capacity connected in series flow relation directly to'each evaporator with the evaporators interconnected in unrestricted series flow relation, and a selection valve positioned to selectively alter the combination of flow restrictor conduits to increase or decrease the direct flow of refrigerant to one of the evaporators.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.

Fig. l is a diagrammatic illustration of a refrigerating system embodying features of my invention and illustrated adapted in a refrigerator cabinet shown in phantom;

. Fig. 2 is a fragmentary view of a control valve used in my invention with parts shown'in section;

Fig. 3 is a diagrammatic illustration of a section of the-refrigerating system illustrated in Fig. 1 embodying a modified form of my invention; a Fig. 4 is a diagrammatic illustration of a'refrigerating system embodying features of a further modified form of my invention; and

Fig. 5 is a diagrammatic illustration of a section of the refrigerating systemillustrated in Fig. 4 embodying a still further modified form of my invention.

Shown in the drawing is a refrigerating system 20 comprising evaporator coils 22 and 24 and a condensing unit 26 comprising a condenser 28 and a motor compressor unit 30. The evaporator coil 22 is preferably located in a compartment 32 of a refrigerator cabinet 34 and is adapted to cool and maintain the compartment at relatively high temperatures for the storage of articles of food requiring temperatures above 32 degrees Fahrenheit. The evaporator coil 24 is shown coiled about and bonded to a liner 36 forming the walls of a compartment 38 and is adapted to cool and maintain the compartment at relatively low temperatures for the freezing and storage of articles of food requiring temperatures below 32 degrees Fahrenheit. The condensing unit 26 is preferably positioned within a machine compartment 40 provided in the lower portion of the cabinet 34.

The motor-compressor unit 30 of the condensing unit 26 is connected by a conduit 41 to the inlet of the condenser 28 whose outlet is connected by conduit 44 to a tank or receiver 46. The outlet of the receiver 46 is interconnected to the inlet of the evaporator coil 22 by a small diameter conduit 48 which is bonded in thermal heat exchange relation with a return conduit 50 that interconnects the outlet of the evaporator coil 24 with the motor compressor unit 30. The outlet of the evaporator 22 is connected to the inlet of the evaporator 24 to be in series flow circuit by means of a small diameter or restrictor conduits 52 and 54 under the control of a solenoid or electro-magnetically operated valve 56.

The electro-magnetically operated valve 56 comprises a valve body 60 having formed therein an inlet chamber 62 with opposed outlet passageways 64 and 66 extending therefrom. The inlet chamber 62 is in open communication with the evaporator 22 through a conduit 68. Adapted to seat over the entrances and alternately close communication therethrough to passageways 64 and 66 from the inlet chamber 62 is a valve 70 mounted on a stem 72 that extends upwardly into a central opening (not shown) of an electrical coil 74. The passageway 64 is interconnected in open communication to the inlet to the evaporator coil 24 through a restrictor conduit 52, while the passageway 66 is interconnected in open communication to the same inlet of the evaporator through restrictor conduit 54.

To control the cycling operation of the motor-compressor unit 30 there is provided a thermostatically controlled switch having a feeler bulb 82 located in the compartment 32, preferably attached to the evaporator coil 22, to be responsive to the temperature of the com partment to actuate the switch 80. The switch 80 is connected by electric wires'84, 86, 88 in series with the motor-compressor unit 30. The wires 86 and 88 connect to a suitable source of electrical energy.

To control and operate the valve 56 in response to ambient temperature there is provided a thermostatically controlled switch 90 having a feeler bulb extension 92 for placement in the machine compartment 40. The bulb extension may however be positioned in the path of the air entering or leaving the machine compartment, or be located externally of the cabinet to be responsive to the air circulating thereabout uninfiuenced by the heat from the machine compartment. The switch 90 is wired in circuit with the electrical coil 74 of the valve 56 by wire connections 94, 96 and 98. The wires 96 and 98 connect to a suitable source of electrical energy.

In operation heat laden refrigerant vapors are Withdrawn from the evaporator coil 24 through the return conduit 50 into the motor-compressor unit 30 wherein it is compressed and conducted therefrom into the condenser 28 to be cooled and condensed for delivery into the receiver 46 from which the flow is metered by the small diameter conduit to the evaporator coil 22. In

-tions only with the restrictor conduit 110.

the evaporator 22 only a partial evaporation of the liquid refrigerant is necessary to cool the air circulating over the evaporator to maintain the compartment at the desired temperature. From the evaporator 22 the liquid and vaporized refrigerant is directed by the valve 56 to flow through the restrictor conduit .52 to the evaporator coil 24. The restrictor conduit 52 meters theflow from the first evaporator to the second evaporator to maintain a pressure-temperature differential therebetween so,-that the pressure in the evaporator 22 is maintained relatively higher than in the second evaporator 24. This permits the first evaporator to maintain the temperaturein the compartment 32 at above 32 degrees Fahrenheit While the second evaporator 24 maintains the compartment 38 at temperatures below 32 degrees Fahrenheit.

As the ambient temperature remains below 85 F. the valve 56 is deenergized so as to direct the refrigerant flow through the restrictor 52. The thermostatic control 80 will cycle the motor compressor unit in responseto the first evaporator coil 22 and during its operation sufficient refrigerant is conducted through the restrictor to the second evaporator to maintain proper and desired temperatures in the second as well as in the first compartment. As the ambient temperature rises to and above 85 F. the thermostatic control switch 90 will close the electrical circuit to energize the coil 74 which will magnetically attract and lift the valve 70 from its seat over the passageway 66 to seat upon and close the entrance to passageway 64 thereby closing communication through the restrictor conduit 52 and opening communication through the restrictor conduit 54. As the restrictor conduit 54 is of larger diameter with lesser resistance to refrigerant flow than the restrictor conduit 52, as for example the conduit 52 may be 12 inches in length having an inside diameter of .059 inch whereas the conduit 54 may be 6 inches in length having an inside diameter of .064 inch, a greater volume of refrigerant will be conducted therethrough from the first to the second evaporator coil. With the larger restrictor .conduit 54 the pressure differential between the evaporators is reduced during periods of high ambient temperatures providing increased cooling by both evaporators.

In Fig. 3 there is shown a modified control arrangement comprising a restrictor conduit 102 interconnecting the .outlet of a first or high temperature evaporator with the inlet of a second or low temperature evaporator '106, and a second interconnection in parallel with the restrictor conduit 102 comprising a solenoid or electroanagnetically operated valve 108 controlling the inlet to a second restrictor conduit 110. The solenoid valve 108 differs from the valve 56 shown and described in the preferred form in that the valve 108 functions to open and close communication therethrough and here func- The restrictor conduit 110 is of smaller diameter and of longer length than the conduit 102 to permit a lesser flowtherethrough than through conduit 102.

In operation the restrictor conduit 102 provides a fixed pressure differential between the two evaporators and remains in open communication therebetween at all times. When the ambient temperatures rises to 85 F., or above, the solenoid valve 108 is energized in the same manner as described in the preferred form whereupon an additional flow of refrigerant is had through the restrictor conduit 110 with that flowing through restrictor conduit 102 from the first to the second evaporator. The second restrictor conduit 110 provides an additional flow of refrigerant and is arranged with the first restrictor conduit 102 to decrease the pressure differential between the evaporators by the increase flow of refrigerant to the second evaporator so that each may provide proper cooling at desirous temperatures during periods of high ambient temperatures. When the ambient temperature drops below 85 F. the solenoid valve 108 is deenergized to close communication through the restrictor conduit leaving restrictor conduit 102 to regulate and con trol the flow between the evaporator coils.

In Fig. 4 there is shown a further modified form of a two temperature refrigerating system comprising a first or high temperature evaporator coil 122, a second or low temperature evaporator coil 124, a motor-compressor unit 126, a condenser '128, a tank or receiver 130, and a two way solenoid or electro-magnetically operated valve 132. The valve ,132 is similar in construction and operation to that shown and described in Fig. 2. The first evaporator 122 is connected in unrestricted communication with the second evaporator 124 through conduit 134 for conducting refrigerant from the first to the second evaporator. Vaporized refrigerant in the second evaporator is withdrawn through a return conduit 136 by the motor-compressor unit 126 wherein it is compressed and delivered to a condenser 128 to be cooled and liquified for delivery to the receiver 130.

The receiver 130 is interconnected; by a. srnall, diameter metering conduit to a T connection 1 2 which is interconnected through a small diameter-conduit 144 to the inlet of the first evaporator 122 and through an unrestricted conduit 146 to the inlet of the valve 132. The valve 132 is provided with two. outlets which are interconnected to the inlet of the second evaporator by restrictor conduits and 152 respectively. The-;.restrictor conduit 150 is arranged to provide a larger --volume of refrigerant flow therethrough than through the restrictor conduit 152 which is of smaller cross sectional diameter and of longer length than restrictor conduit 150. The electro-magnetically operated valve is operably energized by a thermostatic control element 156 which is responsive to the ambient temperature, preferably to the temperature of the air circulating about the motor compressor and condenser, though the control element here and in the preferred form may be positioned so as to be responsive to the air circulating about the refrigerator cabinet uninfluenced by the heat from the compressor and condenser.

During periods when the ambient temperature is normal, that is below 85 degrees fahrenheit, refrigerantis metered from the receiver 130 by the small diameter conduit 140 which conducts the refrigerant to the T connection 142 where a proportionate amount is metered and conducted by the restrictor conduit 144 to the first evaporator, the remaining portion of the refrigerant is conducted through conduit 146 from which is directed by the valve 132 through the restrictor conduit 150 into the second evaporator. The electro-magnetically operated valve 132 is deenergized during this period to direct the refrigerant flow through the restrictor conduit 150. The restrictor conduit 150 regulates or meters the flow to the second evaporator and also provides suflicient pressure in the conduit 146 to provide sufficient pressure flow differential across the restrictor conduit 144 so that a normal meteredflow of refrigerant is conducted directly into the first evaporator for cooling after which it is conducted to the second evaporator 124 through unrestricted conduit 134.

When the ambient temperature rises to or above '85 degrees fahrenheit the thermostatic control element '156 will energize the electro-magnetically operated valve 132 which then will close communication to the restrictor conduit 150 and direct the flow of refrigerant from conduit 146 to and through the restrictor conduit 152 and into the second evaporator 124. As the restrictor conduit 152 has a smaller flow capacity than restrictor conduit 150, the increase resistance will further reduce the direct flow into the second evaporator to increase the pressure in the conduit 146 to accelerate the refrigerant flow through the restrictor conduit 144 to the first evaporator by the increase in pressure differential between the inlet and outlet of the conduit 144. 'By this arrangement the first evaporator is assured of an adequate flow of refrigerant during periods of high ambient temperatures when the tendency of the motor-compressor unit is to operate on longer on cycles resulting in increasing the suction pressure, that is, lowering the pressure at the outlet of the second evaporator whereby with the use of the restrictor conduit 150 there would be an increase flow directly into the second evaporator and a reduction in the flow to the first evaporator. By changing the refrigerant flow so as to be directed through the restrictor conduit 152 more refrigerant is available to fiow directly into the first evaporator without effecting the operation of the second evaporator which receives an unrestricted flow from the first evaporator and a restricted flow through conduit 152.

In some instances of operation it is found that the high temperature evaporator 122 may operate at too low a temperature. Under these conditions a different arrangement of restrictors 150 and 152 is made. In Fig. I have shown these two restrictors reversed in their relationship with valve 132. Thus when the temperature of evaporator 122 is too low the valve 132 is energized to permit refrigerant to flow through the restrictor 152 and stop the flow of refrigerant through restrictor 150 as takes place during normal operation. In this instance the valve 132 may be controlled in response to changes in temperatures of evaporator 122 instead of the ambient air in the machine compartment.

The electro-magnetically operated valves described above may if desired be connected in an electrical circuit with a manually operated switch (not shown) so that the user may manually control the valves operation to suit his refrigeration needs.

Although preferred and modified forms have been illustrated, and described in detail, it will be apparent to those skilled in the art that various other modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claim.

I claim:

In a two temperature refrigerating system comprising two evaporators in series flow circuit and a condensing unit, a conduit interconnecting the outlet of the second evaporator in said circuit with said condensing unit, a small 'diameter conduit interconnecting said condensing unit with the inlet of the first evaporator in said circuit for regulating the flow of refrigerant thereto, two restrictor conduits each interconnecting the outlet of said first evaporator to the inlet of said second evaporator to regulate the flow of refrigerant from said first to said second evaporator to maintain said first evaporator at relatively high temperatures and said second evaporator at relatively low temperatures, an electro-magnetically operated valve positioned to control the flow through each of said restrictor conduits, one 0g said restrictor conduits formed to permit a greater flow of refrigerant therethrough than through the other of said restrictor conduits, thermostatic control means operably connected to energize or deenergize said electro-magnetically operated valve, said thermostatic control means being responsive to ambient temperature about said condensing unit to energize said electro-magnetically operated valve when the ambient temperature rises to or above a predetermined value and to deenergize when below said value, said valve arranged with said restrictor conduits to direct the flow of refrigerant through said restrictor conduit of greater flow capacity when energized and when deenergized to direct it through the said restrictor conduit having the smaller flow capacity.

References Cited in the file of this patent UNITED STATES PATENTS 2,128,020 Smilack Aug. 23, 1938 2,172,129 Philipp Sept. 5, 1939 2,667,757 Shoemaker Feb. 2, 1954 2,693,679 Staebler Nov. 9, 1954 2,733,574 Reber Feb. 7, 1956 2,769,312 Harrold et a1 Nov. 6, 1956 2,777,297 Doeg Jan. 15, 1957 

